If they succeed then aren't they an acceptable fit for the role? If it devalues the role then that means the job isn't as demanding as the title makes it seem.
When I said 'success' I meant: 'achieved a basic level of competency after bungling one or several projects, often with unknown or unquantifiable bugs and then move onto the next company / role with few consequences'.
More succinctly: caused harm to others/ project and still got a paycheck.